#include <iostream>
using namespace std;

int main()
{
    double n; cin >> n;
    double l = -1000, r = 1000;
    while(r - l >= 1e-8)
    {
        double mid = (l + r) / 2;
        if(mid * mid * mid < n) l = mid;
        else r = mid;
    }
    printf("%.6f", r);
    return 0;
}